CHEMICAL CONSTITUTION AND PHYSIOLOGICAL ACTION. 721 



minutes, the respiratory movements were laboured, and they occurred only 

 twenty-four times in the minute. The rabbit now lay on the side, quite flaccid 

 and powerless ; and, at times, a series of slight tremors occurred. The respira- 

 tions gradually became weaker and less frequent, the common sensibility dis- 

 appeared, and death occurred, twenty-two minutes after the administration. 



Three minutes after death, the exposed heart was contracting in normal 

 rhythm, at the rate of seventy-four beats in the minute ; and it was ascertained 

 that the conductivity of the afferent and efferent nerve fibres of the sciatic nerves, 

 the reflex function of the spinal cord, and the contractility of the striped muscles 

 were still retained. 



This description is sufficient to show that in rabbits hydrochlorate of methyl- 

 conia produces very similar effects to hydrochlorate of conia. That this similarity 

 also occurs in frogs will be seen from the following experiment. 



Experiment LXXXVL— A solution containing six-hundredth s of a grain of 

 hydrochlorate of methyl-conia, in five minims of distilled water, was injected 

 under the skin at the right flank of a frog, weighing 185 grains. In ten minutes, 

 a slight degree of stiffness, with rigid elevation of the fingers, was present in the 

 anterior extremities, but the frog still jumped about actively. Gradually the 

 movements became less energetic; some sprawling occurred; and, soon, the frog 

 lay on the abdomen and chest, quite unable to jump or move about. In twenty 

 minutes, the power of voluntary movement was completely lost, and irritation of 

 the skin caused but feeble reflex twitches in both posterior extremities. The frog 

 remained in this state until forty-seven minutes after the administration ; but in 

 fifty minutes, the most severe stimulation of the skin was unable to excite any 

 reflex movement whatever. The right sciatic nerve was now exposed and 

 galvanised ; twitches were thereby excited in the right toes, but these were 

 unaccompanied by any movement in the left posterior extremity or elsewhere. 

 At this time the cardiac impulse was of fair strength, and the contractions of the 

 heart were occurring at the rate of forty in the minute. 



On the morning of the following day, the frog was dead and in rigor. 



These symptoms agree closely in their general character with those described 

 after corresponding doses of hydrochlorate of Dr Christison's conia (Experiment 

 LXL), and of Mr Morson's conia (Experiment LXXVI.) ; but the slight spasmodic 

 symptoms that appeared in the anterior extremities were not invariably observed 

 in our other experiments with this substance. Paralysis is shown to be the pre- 

 dominant symptom, and the causation of this paralysis, after the small fatal dose 

 exhibited in this experiment, appears to be due to an abolition of the reflex 

 function of the spinal cord, rather than to a suspension of the conductivity of 

 motor nerves. The action of hydrochlorate of methyl-conia, therefore, apparently 

 resembles that of hydrochlorate of Morson's conia ; and we shall see from the 

 following experiments that the special variations pointed out as occurring with 

 vol. xxv. part II. 9 J3 



